Psych Midterm #2

1. Acquire and use vocabulary from the field of genetics (e.g., exon, promoter, methylation)

2. Consider the molecular consequences of genetic mutations and their role in evolution

3. Understand the basics of gene regulation, including epigenetic regulation

introns

sections of mRNA that do not code for protein, removed

exons

sections of mRNA that code for protein, spliced w other exons to make final mRNA

dna methylation

inhibits transcription/turns gene off by adding a methyl group to cytosine

reversible

can be passed down

histone acetylation

histone opens up so DNA can be accessed to be transcribed

reversible

can be passed down

training fear into mouse

via a scent, offspring’s glomerulus(olfactory bulb in brain) is much larger, fearful of that scent only

training w acetophenone (fear conditioning) reduced methylation of M71 gene (odor receptor) in sperm → higher transcription rates

polymorphisms

variations in gene sequence that are established in population ( > 0.5%)

• single nucleotide polymorphism: (SNP) polymorphism only affecting 1 nucleotide

alleles

different version of same gene within a population

• homozygous: if 2 copies of same allele

• heterozygous: if 2 different alleles

humans are diploid

mutations

point mutation: 1 nucleotide change

messes up entire protein

changes:

• function of product (if in exon)

• how much is expressed (if in intron)

• where it is expressed (if in intron)

• when it is expressed (if in intron)

drosophila melanogaster experiment

70% of pop is rover (long foraging path)

30% of pop is sitter (short foraging path)

wondered if a gene determined path length? → ‘for’ gene (foraging) encodes PKG → parental cross gives Ff rovers(FF x ff) → F2 cross gives 3 rovers, 1 sitter (FfxFf)→ sequenced gene to find that there are 300 SNPs btw rover & sitter alleles

• most of genetic differences are in introns of gene which are regulatory in nature → controls how much/when/where gene is expressed

transcription factors

enhance/suppress gene transcription

mutations in promoter region can affect how much a gene is expressed

methylation of CpG sites affects transcription factor binding

disassortative mating

non-random mating pattern of individuals w dissimilar phenotypes

white-throated sparrows

practice disassortative mating

white-striped & tan-striped phenotypes

• white striped have higher singing rates & more aggressive than tan striped → behavioral difference caused by ‘supergene’

• tan striped have 2 copies of ZAL2 chromosome (homozygous) while white striped have only 1 copy of ZAL2 and an inverted ZAL2m copy (heterozygous)

• inverted copy creates super gene

because of disassortative mating

birds that are homozygous for supergene ZAL2m are rare and aggressive

AMV

part of social behavior network in brains of all vertebrates

inside inverted chromosome is gene

ESR1→ encodes estrogen hormone receptor in brain

• higher in region of white striped birds as early as 7 days old

ZAL2m is expressed more because it is less methylated than ZAL2 → caused by issues in non-coding regions of gene

experiment w ESR1

hypoth: morph diff in ESR1 receptor population caused aggression then estrogen treatments should induce more aggression in WS than TS birds

• was correctttt

researchers deactivated the ESR1 mRNA and it prevented estrogen-induced aggression

1. Understand that animals do not perceive the world the same way we do (Umwelt)

2. Consider features of sensory systems as adaptations shaped by natural selection

3. Explore ways that nervous systems have evolved to solve problems, e.g. sound localization

neuroethology

study of neural basis of natural behavior

• how neural mechanisms have evolved to solve everyday problems, adaptive features of NS

krogh’s principle

for any study there is a perfect/convient study animal

umwelt (tick)

the world that each animal perceives and lives in

tick:

• light→ climb

• butyric acid→ drop

• warmth→ seek blood

niko tinbergen

baby birds will peck at anything red

hodgkins & huxley

able to find action potentials in giant squid axons

Roeder

found that moths can hear ultrasonic sounds which travel thru interneurons to motor neurons → contract wing muscle → rapid unpredictable movement to escape predators

sound

travels 340m/s thru air

displacement component:

• distance that smth moves as sound passes thru it

pressure component:

• what humans/vertebrates can hear, measures compression of air molecules & rarefaction of air molecules

• doesn’t give info about direction

sound vocab

wavelength: distance of one cycle

period: time to complete one cycle (wave to wave or trough to trough)

frequency: 1/period, # of cycles per unit of time

human hearing

20 Hz - 20kHz

below is infrasound

above is ultrasound

to do sound localization, need to know

elevation ↑↓

azimuth ←→

distance

motion

pinna

outside part of ear

shape in vital to getting information

filters and gives sound smth to bounce off of

brain compares info from both ears

interaural level difference (ILD)

diff in sound intensity btw ears

interaural time difference

time diff btw sound in ears

• transient disparity: diff in time arrival

• ongoing disparity: phase difference

barn owls

rely on hearing to hunt, localize sound

have asymmetry in ears→ exaggerates interaural level difference → determines elevation

as sound moves from center to either side of owl→ ITD increases

Jeffress model

bilateral delay lines carry impulses from 2 ears to coincidence detectors → each coincidence detector fires maximally when impulses from 2 ears arrive simultaneously → ITD is represented by which coincidence detector fires the most

ITDs are mapped in

nucleus laminaris, info is converted from place → time → place again

info on azimuth & elevation is integrated in

the midbrain

each neuron has a receptive field corresponding to a location in space

types of rhythms

diel: 24 hours

diurnal/nocturnal: day/night

circadian: 24 hours

infradian: longer than 24 hours

ultradian: shorter than 24 hours

circatidal: w tides, 13 hours

circalunar: w moon phases

circannual: w seasons

circadian

can free run under constant condition in any organism

• no brain needed

• rhythm is organized at cellular level

actogram

x axis: time of day

y axis: days

dark bands: periods of high activity

rhythmic gene activity

clock complex → 1. turns on gene transcription → per/tim mRNA → 2. proteins translated → per/tim protein → 3. Per/Tim complex forms → complex → inhibits clock complex

Per rhythms in fruit flies

flies were genetically engineered so that PER promoter drove expression of luciferase (causes glowing) → flies glowed during high PER transcription

SCN

in hypothalamus

info about light travels to SCN from retina

pacemaker for circadian rhythms

tau mutants hamsters

have shortened circadian rhythm compared to wild type hamsters

when SCN was lesioned → natural rhythm was lost

when SCN was restored→ natural rhythm was restored

1. Explore the molecular, neural, and endocrine mechanisms underlying biological rhythms (e.g., circadian rhythms and annual reproductive cycles)

2. Interpret an actogram

3. Understand how seasonally breeding animals use daylength to know when it’s time to breed

4. Learn about some basic principles of endocrine systems, such as negative feedback loops

5. Consider the bidirectional causality between hormones and behavior

gonadal regression & recrudescence

photoperiodism

seasonal rhythms (breeding) are driven by day length

determined by pineal gland: secretes melatonin during dark

• in animals w/o cerebral cortex→ pineal gland has photoreceptors instead

melatonin

duration of secretion is determined by duration of night

• inhibits gonadal growth in long-day breeders

• stimulates gonadal growth in short-day breeders

• stimulates reproductive activation in fall breeders

• inhibits reproductive activation in springtime breeders

photosensitive hypothesis / coincidence model

Photosensitive factor that detects light (mostly occurs during dark for short days), when occurs at same time at light → triggers hormone release

Longer days = overlap of light and photosensitive factor → hormone release (plasma LH)

photostimulation occurs upon exposure to light & internal photosensitive factor that oscillates on circadian rhythm (peaks in evening) → a light pulse in evening triggers release of reproductive hormones→ Periodic oscillation in sensitivity to light persisted for at least 5 circadian cycles

hormones

circulate thru blood

neuroendocrine communication: hormone made by or that target brain cells

HPG axis

hypothalamic-pituitary-gondal axis, hypothalamus releases GnRH which goes to pituitary (also the sunlight hormone from earlier) which secretes LH/FSH travels to testis/ovary which release testosterone/estrogen

HPA axis: hypothalamus releases CRH which makes pit gland release ACTH which releases cortisol

• cortical suppresses HPG axis

rodent sex

female must lordosis/be receptive for copulation to occur, under hormone control → ovarian steroid hormones: progesterone, estradiol/estrogen

hormones don’t cause behavior

they only make it more likely

testosterone

doesn’t:

• make u violent, dominant, predict athletic ability, take risks

is increased by:

• fighting, winning, competing, risk taking

decreased by:

• parenting

prolactin

parenting also increases prolactin (higher in males w infants/carry infants) testosterone didn’t change, but changing amount of prolactin doesn’t affect parenting behavior in male marmosets